Hi, This sounds very much like my experience with our 8.5 kw Ecodan PUHZ-8.5VAA ASHP & HWC system installed about a year ago. 3 pumps were running continuously. I contacted the Installer. The cause was FREEZE STAT MODE. When outside temp drops below a certain level, (I think 5 deg. C , but not sure) the pumps run to prevent the Heat Pump freezing when inactive. This is the default installation setting unless Anti-freeze is added to the water in the heating circuits. My Installer came back and added Glycol to the system. It had to be pumped in as the system is under pressure of 1 to 1.5 bar. Once this has been done, FREEZE STAT MODE can be disabled. Obviously, this mode should not be disabled unless Anti-Freeze has been added to the system to the correct concentration. Check with a qualified Installer.
